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基于流体力学和水力学基本理论,通过6个糙度、5个流量和5种雨强组合条件下的放水冲刷和模拟降雨试验,研究雨强和糙度对坡面流水动力学特性的影响。结果表明:在坡面薄层水流中,床面糙度对坡面流阻力有“增阻”效应,但在粗糙尺度为1.77 mm时产生拐点;降雨条件下,坡面流自由表面失稳的动态演化过程显著,其波动临界条件为黏深比0.382 4、0.599 3,在整个动态过程中阻力系数都随着降雨强度增加而减小;结合黏滞阻力、雨强阻力构建层流过渡区阻力计算公式,决定系数为0.92(P<0.05),可以较好地为坡面流模型的建立提供参考依据。研究成果有助于从泥沙运动力学的角度揭示坡面流层流失稳的本质,为坡面流理论的发展奠定基础。
Based on the basic theories of fluid mechanics and hydraulics, the influence of rainfall intensity and roughness on the hydrodynamic characteristics of the slope surface was studied by the scouring and draining tests with 6 roughness, 5 fluxes and 5 rainfall intensity combinations. The results show that the bed surface roughness has a “resistance increase” effect on the flow resistance of the slope surface, but the inflection point is produced when the roughness scale is 1.77 mm. Under rainfall, the free surface loss of slope flow The steady dynamic evolution process is remarkable with the critical condition of the wave viscosity being 0.382 4 and 0.599 3. The drag coefficient decreases with the increase of rainfall intensity in the whole dynamic process. The transition of laminar flow is constructed by viscous resistance and rain resistance The calculation formula of zone resistance has a coefficient of determination of 0.92 (P <0.05), which can provide reference for the establishment of slope flow model. The research results help to reveal the essence of the instability of the laminar flow in the aspect of sediment mechanics and lay the foundation for the development of the theory of slope flow.